the united nations and from a program says the burning of coal is the single most largest anthropogenic source of mercury air emissions, have a more than tripled since 1970. coal burning is increasing alongside at it -- alongside economic growth. this is from a report. there was a report done by the university of texas that showed a statistically significant link between pounds of industrial release of mercury and increased austism rates. autism prevalence was reduced by 1% to 10% from the pollution source. the background of the study was that during the time the studied by the texas team, they quoted the us epa estimating environmental mercury releases at 158 million tons annually nationwide in the late 1990's. when will -- are you aware of any studies other than this texas study that has a link between neurotoxic chemicals and the environment and increased rates of autism ? >> i am aware of other studies, for instance the one i mentioned earlier, looking at auto emissions and pregnancy early in life. clearly an association between that exposure and autism rates. >> the have probably g